Comparing LP to Oil

Mike E_2

Here in SE Wisconsin, oil is $2.17/gal, and propane is $1.70/gal. (Although one of my neighbors locked in propane at $1.40/gal) So a 95% propane furnace is slightly more expensive than a 85% oil furnace.

Here are some calculations I did for someone a while back.
All prices are for 100,000 BTU of usable heat (after equipment efficiency).

PROPANE : 80% : 95%

1.40/gal ::::::: 1.91 : 1.61

1.50/gal ::::::: 2.04 : 1.72

1.60/gal ::::::: 2.18 : 1.84

1.70/gal ::::::: 2.32 : 1.95

1.80/gal ::::::: 2.46 : 2.07

1.90/gal ::::::: 2.60 : 2.18

2.00/gal ::::::: 2.73 : 2.30

OIL ::::::::: 75% : 85%

1.80/gal : 1.73 : 1.52

1.90/gal : 1.82 : 1.61

2.00/gal : 1.92 : 1.69

2.10/gal : 2.01 : 1.78

2.20/gal : 2.11 : 1.86

2.30/gal : 2.20 : 1.95

2.40/gal : 2.30 : 2.03

Wayco Wayne_2

A customer

wants a boiler for an in slab radiant floor in a new home being built. I would like to put in an LP mod con boiler for its low temp acceptance and modulation capabilitys, however, they are used to oil and are asking why not an oil boiler and how does they compare in operating pricing. If thay could read my mind they would hear an pinging echoing sound cuz I dont know. Someone put an energy calculator on The Wall a little while ago and I swear I saved it but now when I need it I can't find it. Any help would be appreciated. WW

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Brad White_9

Depends on cost of fuel and other factors of course.

If you can keep oil at 80% steady state AFUE and propane/LP at 90% with a mod-con, that is a good place to start your assumptions. (Boiler low temperature protection of course is your domain, understood, Wayne).

A gallon per hour of 140,000 BTU oil at 80% will yield 112,000 BTUH to the space.

A gallon per hour of 91,600 BTU propane at 90% will yield 82,440 BTUH to the space.

For propane to be valid it would have to cost 74% of the cost of oil, per gallon. Of course your prices can change all over the place.

Joe Brix

If they're used to oil

Give them the best efficency you can with oil. 3 pass cast iron boiler from your favorite manufacturer with a reverse indirect for DHW. Mix down for the radiant. You'll use the BTU's stored up in the tank. Is the extra cost and complexity worth it for 5% more efficency? Find out if they're getting LP appliances and their own burried LP tank.

Frank M Alleva

When energy costs spiked this year, propane oddly enough was the slowest to rise. Do not take this years propane prices as an indication of future product costs when comparing to oil. In the long haul....oil heats best in my book.

Darin Cook_2

Wayne

Are they going to have a gas dryer, stove, fireplace, bbq grill? If they are, then the more you use of LPG then the cheaper it gets. Which boiler will probably stay closest to its peak operating efficiency during its life span? The mod/con will in my book. Which boiler would you rather clean each year? The one that doesn't smell and ruin your clothes I would imagine. Which boiler is quieter and less of a disturbance? Thats a no brainer. No one has a graph or table to show you the cost of operation of a modulating piece of equipment because there are too many factors involved. But I think you already know what will be cheaper to operate and in the best interests of the customer.


Darin

harvey

LP or OIL

I think Darin hit the nail on the head. You have to look at the BIG picture. Then it's a NO brainer unless electric is cheaper than LP.

hr

The modulating feature

with gas or LP equipment is a big plus and an amazing energy saver.

There's a handful of use here that switched from basic gas or LP fired to Mod-Cons and have saved 30- 40% in fuel use.

I went from a high 80% Weil GV Gold to a Knight 90% Mod-Con and have reduced my propane consumption by 30%!

So a direct comparison is hard to figure when you use the published numbers.

On the plus side gas or LP fired Mod-Cons are very small, quiet, sealed combustion, have great onboard microprocessors, outdoor reset, DHW priority, data logging, PC interface, and a lot more as standard equipment.

Be sure to compare the features and benefits.

hot rod

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soot_seeker_2

so what would be cheaper to run right now oil in my area is $2.25gal i don't have natural gas in my area but i can get propane. should i go gb142 or g115? i heat with baseboard

Wayco Wayne_2

I think I will stick with LP

I had designed the job for nat gas but the gas company didnt come through and priced running a line to their house at 30K. Wow! The house is superinsulated. R38 in the Walls and R78 in the ceilings. The 6000 sq ft slab water temp is 95 at 10 degrees outside temp. I have 6 supplemental panel rads designed to work at 140 at design temps so the boiler can condense almost all the time. If I went cast iron I would have to step the temp down twice for heating the 2 different heat emmiters and then take care to protect the boiler. I hope to talk them into some solar back up in the future. WW

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scrook_2

Oil vs LP cost

w/ oil at $2.25/ gal, propane (LP) should be about $1.47/gal (91,500 vs 140,000 BTU/gal), however conventional LP equipment will be slightly less efficient (say 81-82% vs 84-85%) and condensing LP equipment will be somewhat more efficient (say 88-90%), so you must factor that into the equation too along w. initial equipment cost, regular maintenance costs, reliability/complexity, and the possibility of also using LP for cooking, cloths drying, etc., and the differant storage requirements (inside for oil, outside on or below grade (buried) for LP. fuel cost is only one (if not an unimportant one) piece of the decision.

Note that the ratio of LP to oil price may change some year to year too, though they should roughly track in the long run.

I use (and like) oil for heat and use natural gas for drying/cooking (& hot water, as I don't have an indirect on by boiler -- maybe someday when the HW heater dies...), but think I'd look at LP only vs. LP + oil if I was where no NG was available, but, as they say, "it depends".

S Ebels

Wayne

I'll try to attach a chart I downloaded from Energy Information Agency for you. It's in Excel spreadsheet format and allows you to input your local pricing and efficiency of the appliance used.

S Ebels

Wayne

I'll try to attach a chart I downloaded from Energy Information Agency for you. It's in Excel spreadsheet format and allows you to input your local pricing and efficiency of the appliance used. Save it on your computer, it's a handy calculator to have.

Wayco Wayne_2

Thank you Steve

This wil be most useful. WW

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